Conventionally, alcohol compounds have been widely used as components or synthetic intermediates and the like for various pharmaceuticals, agricultural chemicals, flavors, fragrances, or commodity chemicals. As methods for producing such alcohol compounds, methods by which an alcohol compound is obtained by hydrogenation of an aldehyde compound have been known to be useful methods. In this connection, various catalysts and reaction modes have been proposed for the hydrogenation reaction. A method by which, among aldehyde compounds, an α,β-unsaturated aldehyde is selectively hydrogenated to obtain an allyl alcohol is said to be particularly useful.
As methods for obtaining an alcohol compound by a heterogeneous catalyst reaction in which an aldehyde compound is hydrogenated, methods have been known which use an iridium catalyst, an osmium catalyst, a palladium catalyst, a nickel catalyst, a platinum catalyst, a ruthenium catalyst, or the like, as described in Non-Patent Document 1 and Non-Patent Document 2, for example. However, these methods often requires harsh reaction conditions such as high temperature or high pressure, and are severely limited in terms of operability, production apparatus, and the like. Moreover, particularly in the cases where an α,β-unsaturated aldehyde is used as the hydrogenation substrate, there is a problem that the selectivity is generally low.
Meanwhile, as methods for obtaining an alcohol compound by a homogeneous catalyst reaction in which an aldehyde compound is hydrogenated, methods which use a complex using a platinum group metal and other methods have been known (for example, see Non-Patent Document 3 and Patent Document 1). However, such a complex uses a platinum group metal, which is expensive. Hence, there are problems from the economical view point that the complex is expensive and that the influence of fluctuation of the price of a metal of interest is large. Moreover, there is a problem that, when an α,β-unsaturated aldehyde is used as the hydrogenation substrate, iridium complexes, rhodium complexes, and osmium complexes have low selectivity.
In recent years, a method has been reported in which an aldehyde is hydrogenated by use of a catalyst made of a copper compound and dimethylphenylphosphine (Non-Patent Document 4). However, there is a problem of operability because it is necessary to use dimethylphenylphosphine, which is unstable in the air, and highly smells, in an excessive amount with respect to copper. In addition, there also is a problem of cost effectiveness because the catalytic activity is low, and consequently it is necessary to use a large amount of the catalyst (2 to 5 mol % in terms of Cu). Meanwhile, in Non-Patent Document 4, a method is developed which uses [(tripod)CuH]2 as the catalyst, also. However, the method has the following problem. Specifically, since the catalytic activity is extremely low, it is necessary to use a tridentate ligand Tripod in an excessive amount with respect to copper for the reaction to be completed, even when the catalyst is used at 2.5 mol % with respect to the substrate. In addition, there is a problem of operability because the range of pressure for the reaction to proceed is from 50 to 70 psi (approximately 0.35 to 0.5 MPa), which is extremely narrow.
Note that, in Patent Document 2 and Non-Patent Document 5, a catalyst for a homogeneous asymmetric hydrogenation reaction has been developed using a copper catalyst. However, this is a method for obtaining an optically active compound by hydrogenating a ketone moiety or a double bond of a prochiral unsaturated compound, and neither Patent Document 2 nor Non-Patent Document 5 describes hydrogenation of aldehydes.    Patent Document 1: Japanese Patent Application Publication No. Hei 08-225467.    Patent Document 2: International Patent Application Publication No. WO2007/007646.    Non-Patent Document 1: Handbook of Heterogeneous Hydrogenation, Ertl, G.; Knozinger, H.; Weitkamp, J. Eds., VCH Weinheim, 1997, p. 2186.    Non-Patent Document 2: Muroi, Takashiro, “KOUGYO KIKINZOKU SHOKUBAI (Industrial Noble Metal Catalyst),” 2003, p. 111.    Non-Patent Document 3: Handbook of Homogeneous Hydrogenation, de Vries, J. G.; Elsevier, C. J. Eds., Wiley-VCH Weinheim, 2007, Vol. 1. p. 413.    Non-Patent Document 4: Chen, J.-X.; Daeuble, J. F.; Bresdensky, D. M.; Stryker, J. M. Tetrahedron 2000, 56, 2153.    Non-Patent Document 5: Shimizu, H.; Igarashi, D.; Kuriyama, W.; Yusa, Y.; Sayo, N.; Saito, T. Org. Lett. 2007, 9, 1655.